g0ps

Evidence would always be the same. That which would prove the "psychological incapacity" of either of the spouses. It really depends on the presentation or narration in the petition and testimony tending to prove the same. Otherwise, you will be needing budget for the judge.

If your wife gets pregnant by another guy, that is not a ground for annulment or nullity of marriage. That is however a strong evidence for adultery.

But for the declaration of nullity of marriage, that's a bit far fetch. It will depend on the ingenuity of your lawyer to establish that "having another man" constitutes psychological incapacity on the part of wife. You would also be needing a good report from a psychologists. With that said, let's be realistic.. if you pay the right price to the right people, (you know what i'm saying? ) you will most likely get your nullity in about a year's time.

You can file a criminal case for adultery against the wife, which would also include the other guy in the charge.